ContentCatalog#addFile should return file added
The ContentCatalog#addFile should return the file object that it just added. Currently, the method returns nothing.
We had held off on returning a value from this method because we weren't sure what it should return. After using it in several real-world scenarios, it's obvious that the method should return the file added. Otherwise, it requires going back to the content catalog to look up the file, which is both inconvenient and inefficient.